The beginning of a two-day, one-night anal training hot spring trip with Yukina-chan, the owner of a beautiful buttocks yet to have anal experience. Using fingers to loosen her sensitive anus, thrusting a wet tongue into it and licking it thoroughly. When inserting a penis into the still tight anal hole, the buttocks' indentation sucked it in like a suction cup with a little "chuu". Enjoying the different sensations by alternating between the vagina, mouth, and intestines. Training all the holes and repeatedly reaching climax with the anus wide open.
